Don't cap num_cores at 32 on 32-bit Windows.

See here for a similar change in Ninja.  Wanna bet they just got Z840s too?
https://github.com/martine/ninja/commit/8c8834acffdc0da0d94119725929acc712c9dfad

BUG=skia:

Review URL: https://codereview.chromium.org/1213063011
diff --git a/src/core/SkTaskGroup.cpp b/src/core/SkTaskGroup.cpp
index 4504def..e809f57 100644
--- a/src/core/SkTaskGroup.cpp
+++ b/src/core/SkTaskGroup.cpp
@@ -16,7 +16,7 @@
 #if defined(SK_BUILD_FOR_WIN32)
     static void query_num_cores(int* num_cores) {
         SYSTEM_INFO sysinfo;
-        GetSystemInfo(&sysinfo);
+        GetNativeSystemInfo(&sysinfo);
         *num_cores = sysinfo.dwNumberOfProcessors;
     }
 #else